The use of polymeric base in imaging members is well known. Typically, the base of the imaging member comprises a hydrophobic polymer, and the image receiving layer comprises hydrophilic colloids, such as gelatin.
Hydrophilic colloids such as gelatin have many unique and desirable properties that make them especially useful in the preparation of photographic materials. For example, gelatin has high swellability in aqueous media which allows rapid diffusion of compounds in and out of a gelatin-containing photographic layer during film processing. Gelatin is also an excellent dispersing medium for light-sensitive silver halide grains and aqueous gelatin solutions exhibit excellent coating properties and quickly undergo gelation when chilled; all of these properties are critical to the manufacture of photographic films. In case of inkjet applications, the ability of gelatin containing layers to absorb water and water-based inks has promoted their use in inkjet image receiving media. In addition, crosslinked gelatin layers provide very good physical properties such as resistance to scratch, abrasion, ferrotyping, and blocking.
It is difficult to adhere photographic emulsions to oriented polyester supports, such as polyethylene terephthalate or polyethylene naphthalate. The primer layer must work both with unprocessed and processed film in the dry state, and must also adhere when the film is wet during the development process.
Several adhesion promoting “subbing” materials, such as poly(methyl acrylate-co-vinylidene chloride-co-itaconic acid) and poly(acrylonitrile-co-vinylidene chloride-co-acrylic acid) disclosed in U.S. Pat. Nos. 3,201,249 and 3,143,421, respectively, provide the required adhesion when applied before orientation but are not as effective when applied on oriented polyester support. The effectiveness of these adhesive materials may be enhanced by the use of swelling or attack agents such as resorcinol.
An alternative approach disclosed in U.S. Pat. No. 4,695,532 describes a discharged treated polyester film support having coated directly thereon a crosslinked layer of an aqueous vinyl acrylate copolymer and gelatin mixture. Although this system has good adhesion before processing, the adhesion performance is severely degraded by photographic developing solutions.
U.S. Pat. No. 5,298,192 discloses a subbing layer comprising a dye, a hydrophilic colloid, and a latex. But this layer needs to be applied to an already existing subbing layer coated on the support. Such a two-step coating process is costly and introduces more waste.
U.S. Pat. Nos. 4,695,532 and 4,689,359 describe a discharge treated polyester film support having coated directly thereon a subbing layer comprising a mixture of gelatin and an aqueous vinyl acrylate copolymer having a ratio of gelatin to polymer of between 5:95 to 40:60 and a dry coverage of between 0.11 and 0.55 g/m2. Although this subbing layer has good adhesion before processing, it has been found that adhesion after contact with photographic developing solutions is severely degraded.
U.S. Pat. No 5,639,589 describes a subbing composition comprising a mixture of gelatin and an aqueous vinyl acrylate copolymer described in U.S. Pat. Nos. 4,695,532 and 4,689,359 having a ratio of gelatin to polymer of between 55:45 to 97:3. This subbing layer performs well when poly(ethylene naphthalate) is glow discharge treated. But poor adhesion, especially when the film was in contact with wet processing solution, was found when it was applied to poly(ethylene terephthalate).
EP 0583787 A2 discloses the use of glow discharge treatment to enhance the adhesion of photographic elements. This treatment involves the use of high energy plasma under vacuum which requires specific equipment.
U.S. Pat. No. 5,378,592 discloses the use of a two-layer subbing layer (for photographic materials) wherein the first subbing layer is a layer of polyurethane latex cured with an epoxy compound or a dichloro-s-triazine derivative, and the second subbing layer is a hydrophilic colloid layer comprising gelatin.
U.S. Pat. No. 5,532,118 describes the use of a layer of a self-crosslinking polyurethane as an adhesion promoting material for polyester film support. U.S. Pat. No. 5,910,401 describes a similar use of a gelatin-grafted polyurethane for adhesion promotion.
Use of polyethyleneimine based primer layers on polypropylene substrates is known in the art. For example, U.S. Pat. No. 4,663,216 discloses a polyethyleneimine-primed synthetic paper substrate for allegedly improved ink absorption. U.S. Pat No. 5,248,364 and 5,510,180 disclose multi layer laminates containing a layer of a polypropylene material permanently bonded to a polyethyleneimine-primed substrate for packaging. U.S. Pat. No. 5,486,426 discloses use of a polyethyleneimine primer in a cold sealable polyolefin substrate. U.S. Pat. No. 5,776,604 discloses a lithographic printable polypropylene substrate, which is primed with polyethyleneimine. U.S. Pat. Nos. 5,827,615 and 6,013,353 disclose metallized multilayer polypropylene packaging films primed with polyethyleneimine. U.S. Pat. No. 6,232,056 discloses imaging elements with polyethyleneimine fuser layer for backside splice enhancement, particularly heat splicing in high speed photographic printers such as the Agfa MSP printer. U.S. application Ser. No. 10/044,874, filed Oct. 29, 2001 describes the use of a mixture of gelatin and polyethyleneimine to form a primer for an image member, which can include photographic paper or films. For a discharge treated poly(ethyelene terephthalate) film, the primer comprising polyethyleneimine and gelatin provide pre-process dry adhesion and wet adhesion. However, the present invention, with its additional use of a latex, provides superior post-process dry adhesion over the invention of U.S. application Ser. No. 10/044,874, filed Oct. 29, 2001.
There is a critical need to develop primer layers that can be easily incorporated on imaging members, particularly those with highly hydrophobic supports such as oriented polyesters, in order to attain good pre-process and post-process dry adhesion as well as good wet adhesion of image receiving layers, such as those comprising photographic emulsions, on to said supports.